This week, the U.S. Supreme Court heard arguments in a case called Kirtsaeng v. Wiley, which will test the limits of something called the “first sale” doctrine. First sale is the legal doctrine that governs our right to buy, sell, and loan things like CDs, books, DVDs, and any other product that is covered by copyright without first having to obtain permission from the product’s copyright holder.

If the Supreme Court sides with textbook publisher John Wiley and Sons, which sued Thai-born student Supap Kirtsaeng on copyright infringement grounds for buying the publishers books in Thailand and selling them to U.S. college students at a profit, you may no longer be able to freely buy or resell used, copyrighted goods. It could even put a stake through the heart of companies like eBay, Amazon, and Craigslist, all of which deal heavily in the sale of used goods.

Regardless of the outcome of Kirtsaeng v. Wiley, a decision for which is expected in June, there appears to be broad confusion among consumers about what “ownership” really means these days. So, in the spirit of clearing things up, here is a quick rundown of the products that, even though you paid for them, aren’t entirely yours.

Smartphones

While it’s currently legal to buy or sell a used smartphone, the law says you may not necessarily do whatever you like with the device. According to the most recent round of exemptions to the Digital Millennium Copyright Act (DMCA) from the Library of Congress, smartphone owners will soon no longer be allowed to unlock their devices for use overseas or with another wireless provider, unless their current carriers give them permission to do so.

Tablets

Unlike smartphones, which may be jailbroken for the purposes of installing apps not approved by the respective app marketplace, tablets are not exempt, according to the new DMCA rules. The reason being: Jailbreaking requires making changes to the device’s firmware, which is currently a copyright violation, at least when tablets are involved. So, why is it allowed for smartphones and not tablets? Two reasons: First, the U.S. government says the definition of a tablet is still too broad to write in an exemption for devices that fall under that name. Second, because tablets are less widely adopted than smartphones, copyright holders were able to convince the government that adding an exemption for tablet jailbreaking would adversely affect the devices.

In short, if you have an iPad, you’re only allowed to install apps from the iTunes App Store. Try to jailbreak it, and you’ve broken the law.

Kindle e-books

If you think you just bought that Kindle e-book, you’d be wrong. You licensed it – a concept everyone needs to be familiar with these days. Amazon’s Kindle Terms explicitly state that “Kindle Content is licensed, not sold,” and that, “you may not sell, rent, lease, distribute, broadcast, sublicense, or otherwise assign any rights to the Kindle Content or any portion of it to any third party.”

The control Amazon has over your Kindle e-book collection came under intense public scrutiny last week after a woman named “Linn” alleged that the company had shutdown her Amazon account and deleted the entire contents of her Kindle e-reader due to some suspicious activity linked to her account. Amazon later stated that “account status should not affect any customer’s ability to access their library.” But Linn is not the only one who has experienced similar loss of access.

Music

Just like e-books, “purchasing” a song on, say, iTunes does not mean you’ve bought the song itself. Instead, you’ve paid for the right to play that song in your personal life (provided your “personal life” doesn’t involve playing songs for large groups of people). Furthermore, it is – believe it or not – against the law to burn a copy of a song you “purchased” onto a CD, or to give a licensed MP3 file to a friend.

In terms of being able to resell music you’ve paid for, things are even more complicated. A company called ReDigi is currently being sued by Capitol Records for giving users the ability to resell their MP3 files, just as used record stores sold, well, used records. This, despite the fact that ReDigi’s technology automatically deletes the seller’s copy of a song or album when it goes up for sale. And no copies of a track are made — the actual file is transferred from one machine to the other, which the company says is a perfectly legitimate way to resell music. Capitol, of course, disagrees.

Movies and TV shows

Movies fall into the same category as music and e-books. As such, making copies of a DVD, or ripping a DVD so you can watch it on a device that does not have an optical drive, are violations of copyright. Now, if you’re copying DVDs on a small scale, just giving a copy to a friend or relative, then there is little chance that you’ll get served with a lawsuit from the MPAA. But not getting caught and being allowed to do something are, as you likely realized by now, two entirely different things.

Oh, and if you’re wondering, the whole “licensed, not sold” thing goes for digital movies purchased through Amazon, iTunes, and other online digital movie marketplaces, too.

Video game consoles

As with tablets, it is perfectly legal (for now) to resell your used Xbox or PS3. What you may not do is mod your video game console (or handheld gaming device) to run an alternative operating system due to copyright on the device’s firmware. Furthermore, jailbreaking your Xbox (or other console) is also forbidden because, according to the Library of Congress, “video games are far more difficult and complex to produce than smartphone applications” and anti-jailbreaking mechanisms are in place to “protect highly valuable expressive works.”

Apps

Don’t even think about trying to give away or resell any of your mobile apps. Not only is this technically difficult, both Google Play and Apple’s iTunes App Store – the two largest online mobile app marketplaces – firmly forbid the reselling of your apps. According to the Google Play terms of service, customers are not allowed to “copy, sell, license, distribute, transfer, modify, adapt, translate, prepare derivative works from, decompile, reverse engineer, disassemble or otherwise attempt to derive source code from” purchased apps. And Apple goes even further, saying that customers may not “rent, lease, lend, sell, transfer redistribute, or sublicense the Licensed Application,” and must “remove the Licensed Application from the Mac Computer or iOS Device” before reselling the device.

Pre-loaded devices

Which brings us to our final item: Pre-loaded devices. Because of the copyright rules governing e-books, movies, e-books, apps and other software, selling a device that already contains these copyrighted items means you would likely be in violation of intellectual property law were you to do so. So if you were thinking about offloading your old iPod with 40,000 songs already on it to your mom’s best friend, just make sure the RIAA doesn’t catch wind of your little scheme, or you could be in hot legal water.